Advancing age is associated with progressive decline in neuromuscular function, owing to changes in the central nervous system and the musculoskeletal system that dramatically reduces functional independence and quality of life of older adults. An additional and significant concern in the older population is the alarming rate of increase in obesity prevalence. Approximately 40% of older adults are obese and it is estimated that nearly half of adults above 65 years of age will be obese by 2030. The burdening effects of obesity on the aging musculoskeletal system have been linked to falls, mobility impairments and decreased physical activity. However, very little information is available on obesity related changes in functional brain activation during fatigue development, defined as the fall of maximal force-generating capacity, in older adults. Additionally, stress among older adults is a growing public health concern that can adversely impact healthy aging, and can further exacerbate neuromuscular functioning in the obese older population; however, no published data exist to date. The objective of this project is to examine the impact of obesity and stress on neural activation patterns associated with upper and lower extremity neuromuscular function critical to important activities of daily living such as holding/grasping and balance/locomotion in adults 65 years or older. In addition to biomechanical outcomes of neuromuscular function, the proposed work will incorporate functional near infrared spectroscopy (fNIRS) to define the unique patterns of functional brain activity associated with obesity and stress in older adults. Based on our preliminary work, we hypothesize that an obesity-related decline in neuromuscular function across different tasks and stress conditions will be associated with unique neural activation patterns observed in task-related brain regions. The hypothesis will be tested with two specific aims. We will identify obesity-specific neural activation patterns associated with neuromuscular fatigue in older adults (Aim 1) and determine the impact of stress on neuromuscular control and associated neural activation patterns in non-obese and obese older adults (Aim 2). Outcomes expected here are important because they will provide a level of analysis - brain function - that previously has been absent from biomechanical reports of physical functioning with obesity in the elderly. Promoting brain health throughout life is an important public health goal. Thus, this study can be expected to have a positive impact on improving therapeutic/preventive strategies aimed at enhancing brain, and subsequent physical and mental, health for the growing number of obese elderly Americans.